Time travel movies invariably make very little sense, and Source Code looks goofier and more arbitrary than is average:
I mean, why would you build a technology that lets someone go into dead people? And why for the last 8 minutes of their lives? How do you not die if you're in that person when they die? Would a government agency really think it's acceptable collateral damage to sacrifice a train-full of people to prevent a theoretical future attack? Wouldn't you have more people working on it than this?
That said, I would watch Vera Farmiga and Jeffrey Wright in pretty much anything. In a weird way, I think Farmiga has a lot in common with Tilda Swinton. They're both supremely cool actresses when they want to be. Farmiga's not as much of an awesome acting alien as Swinton is, she's somewhat more approachable. But she's definitely a woman who can plausibly cut dead George Clooney, or run a sketchy military installation without a hair falling out of place. I'd love to see her really fencing with someone like Renee Russo did in The Thomas Crown Affair. We need more grown-up movies, and more smolder before the conflagration.